Ongoing game 2/W 150 The Score

Sub-page of OngoingGame2
Ongoing game 2 Move 156  

The same minimalistic approach shows now

 White: 52+1+5.5 = 58.5
 Black: 53+4 = 57

I have to agree that the unclaimed areas are more favourable for Black. It seems that White has lost.

Ongoing game 2. Move 150  

At this moment Black has captured three stones and White has (supposedly) 5.5 komi.

As I have heard the idea is to count safe territory, supposing that yose will divide all remaning points equally.

The result is

 White: 38+5.5 = 43.5
 Black: 35+3 = 38

But it is Black's turn.

dnerra: I think the idea 'only count safe territory' is very useful for early score estimates. They help you decide your strategy. I.e., if your opponent has more secure territory, you maybe shouldn't continue playing for influence (unless you have the chance to create a good framework). Etc.

I think at this stage, however, the only way to make a good count is to look at every local situation, look at the outcome when either side plays first, and then take the average of that (now I am neglecting sente/gote issues, of course).

As an example, take the lower left. The monkey jump is gote here.

If White gets it, the territory will look like you marked it (plus white territory at y, I suppose). If Black plays first, all the x-marked points become his territory. So I would count two more points for Black there than you do.

Of course, it is hard to do this quickly in a real tournament game. But: these small mistakes really add up - I think it is easy to be ten points off.

Ongoing game 2. Move 50  

Dieter: I have used the marked stones to make a few forcing exchanges and added a few points, mostly for Black. (#:-7 I think Holigor sees White's situation too optimistically.)

My count: Black 47 - White 45,5.

The big question is: which is bigger, a or b? Let's count:

Ongoing game 2. Move 50  

B1 makes 10 points, some of which can still be made if White takes the point B1. W2 makes 14 (plus it rescues a white stone), some of which can be made in sente if Black takes W2.

B2 makes one point, W1 makes none.

So, if we consider the B2/W1 exchange, Black is slightly ahead and takes sente. Also, although it is true that in secure territory the game is close, Black has much more yose. White cannot hope to make all three monkey jumps.

Comments and criticism welcome.

Bill Spight: Maybe White a is better than W1.

Also, the exchange of stones in the top right is not an even exchange. If, as is usually the case, it leaves the local count the same, we need to give White 2-3 points for the possibility of capturing the black stone.

A couple of times you (Dieter) have said that Black has more yose. What do you mean by that? Thanks.

What I mean is: we count only the minimal, certain territory for both sides, not the potential territory that can be made or destroyed. That does not give a complete idea, however, of who's in front. It can be that one side is a "maker" in much more situations (and the other a "destroyer"). Take the monkey jumps. We don't count the territory included, but every time Black defends against one, he makes a couple of points, whereas every time White plays one, he destroys points we hadn't counted in the first place.--Dieter

The lower left corner is interesting. It may be a place where the small monkey jump is better than the big monkey jump. The small monkey jump has a sente follow-up.

Small monkey jump (Black tenuki)  

Black has four points in the corner, and the count if Black plays first is 11. (Black counts the five occupied points plus the two marked points.)

Small monkey jump (sente)  

If Black replies the count is 8. So the small monkey jump is a 3 point sente. The large monkey jump is approximately a 2 1/2 point gote, since Black gets 6 points or so after White plays it.

So it looks like the small monkey jump is sente, and therefore we should count the corner as 8 points for Black.

Hmmm. If Black omits B4, White has a three-point sente play. So the small monkey jump is actually an ambiguous move. Of course, that does not matter for estimating territory.

dnerra: It seems that it is better for Black to play tenuki after the B2/W3 exchange, rather than immediately as in the first diagram.

Bill: Actually, W3 is a one-point sente. I did not realize that at first. <sigh> So the small monkey jump is a three-point sente, after all.
However, it looks like I also goofed on the large monkey jump. It looks like it is a 3.75 point gote, and is bigger than the small monkey jump. Details to follow....

dnerra: Hehe, too late Bill, now you have to correct my analysis instead.

Big monkey jump (a)  

(B4 and W5 will be played later.)
Result: +5 points. (Six points in the corner minus the squared point.)

Big monkey jump (b)  

Oops ...this is getting nasty
If White plays next, the result is four points (White a, Black b, White c).
If Black plays next, at a, the result is either 5.5 points (White answers at d) or...

Big monkey jump (c)  

...this diagram. The result is at least seven points. (Add White a, Black b which is too good for White.)

So after Black's play at a in Diagram (b), the result is at least 6.25 points, hence the result in Diagram (b) is at least 5.125 points.

So Diagram (a) is better for White, and the result is that the big monkey jump is three points gote. (Result in the corner is: 5 points if White plays it, 11 points if Black prevents it.)

If I am right, White can therefore choose between a sente small monkey jump or a gote big monkey jump. (Is it this what is denoted by an ambiguous position, Bill?)

Bill: My first mistake was to think that the large monkey jump threatened to kill Black in the corner. Not so.

Black lives with double ko  

B6 is a sacrifice for shortage of liberties, so that White cannot connect at B2 and make a real ko.

Instead, White has but a threat to kill.

White sente  

W1 - B4 is sente. Later B6 - W7 is sente. Black a - White b are miai. Black has four points in the corner. (Black captured one white stone earlier.)
Note that this assumes White's stones on the right are secure, which may not turn out to be the case. But that's good enough for an estimate.

Black plays first  

B1 seals off the corner. Later B3 - W4 is sente. The points a and b mark out the average frontier. Black has 11 points. So if the large monkey jump is orthodox play, the original count is 7.5 and the large monkey jump is worth 3.5 points (miai).

The small monkey jump allows Black to reply to a position worth 8 points, losing on average 1/2 point. The large monkey jump is normally better.

So our estimate of the corner is 7.5 points for Black.

Ongoing game 2/W 150 The Score last edited by PJTraill on February 10, 2019 - 20:05
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